Such a rotor is described in German Patent Applications 10 2008 055 473.1 and 10 2009 045 467.5. In previous constructions the drive of the threaded spindle mechanism mounted on the rotor hub is located at a relatively large distance from the rotor blade, so that access to the drive is difficult for service staff. In some cases the drive is even arranged outside the interior of the rotor hub, so that apart from a further complication as regards accessibility, measures also have to be taken against lightning strikes and other meteorological influences.